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represents a launch or test day, and describes the
events that took place.
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Today we flew our rockets at the new Whalan Reserve launch site. The flight conditions were ideal with very little wind
in the morning, We continued flying the roll corrected rocket
this week as we wanted to do an aerial survey of the new launch
site. The first flight was pressurised to 120psi with just
straight water. We didn't put an altimeter on the rocket
because we didn't know where it was going to end up and
we didn't want to lose the camera and the altimeter. The flight
went very well and the rocket landed right next to dad from
where he was launching.

Whalan Reserve

Setting up for the first launch

Just like X-box in 3D

Close shave

Missed by that much.

The second flight was identical to the first and the rocket
again came down close to the pad. On the third flight we added
the altimeter to see how high the rocket was going. The flight
read out 365' (111m) which was normal for this rocket.

For the fourth flight dad suggested we should add foam to the
water, but without the jet foaming spacer. So we added foam and
launched the rocket. The rocket again went up straight but this
time to 466' (142m). This was considerably higher than we expected. You
could see that the air pulse was a lot longer because of the
foam that was created while the water was poured in and when the rocket was being pressurised.

On the fifth flight we replaced the bottom of the rocket with
a jet foaming configuration. This section comes with its own
fins that aren't roll corrected. The section also has 1L less
capacity. We also filled the rocket with 1500mL of water and foam. The
launch was nice and slow and the rocket arced over in the
strengthening wind. It flew to an altitude of 310'. This wasn't
unexpected because of the lower capacity and the arced flight
path. I also zoomed the slow motion camera on the bottom half of
the rocket to see if I could film it in flight. This is always
tricky as the rocket is hard to chase. (see video)

On the last flight we set up the first rocket again filled with 1500mL and foam
and without the jet
foaming configuration. The rocket went up nice and straight and
this time it flew to 541' (164m)!. This was surprising
as that was another 75 feet higher compared to the previous
flight of the same rocket.

With the rocket not spinning, the video turned out great from
all the flights. On flight 3 and 4 we captured the shadow of the
rocket on the ground as well as the
'Glory' phenomenon that formed around the rocket's shadow.
This is normally due to water droplets in clouds as can be seen
from the air in an airplane, but here it was most likely due to
the dew droplets on the grass. There was a lot of dew when we
arrived at the launch site.

"Come on grandpa, let me
launch it already"

Interesting Foam
Performance

One thing that stood out
on the day were flights #4 and #6 and
their significantly higher altitudes of
466' and 541' compared to the first 3
flights though the only difference was
the addition of bubble bath into the
water. All other parameters were the
same. At first we thought that perhaps
the AltimeterOne may have been giving
the wrong readings or adding a bias each
flight, but flight #5 showed
a lower altitude of 310 feet which
looked about right. For each flight we
always zero the altimeter just before
launch.

The flight time for
flight #4 was 35.9s and for #6 it
was 49.4s compared to an average
of 25.5 seconds for the first three
flights without foam further supporting
the evidence for the higher
altitudes. Lastly the video from
onboard the camera also visibly showed
that the rocket was higher on those two
flights.

The only unconfirmed
parameter that may have made a
difference is the pressure in that we
may have set the pressure regulator to a
higher pressure on those two flights.
The following day I measured the last
pressure setting on the adjustable
regulator and it read 130psi when
filling a single bottle. The top bottle
was also a little more deformed than
normal, so it is possible that the last
flight was at a higher pressure (hence
the higher altitude than #4). Dad though
believes the pressure was reading 120psi
when he closed the valve, the extra
volume of the rocket on the end of the
long hose may have had something to do with
the reading if air was still flowing
into the rocket. We always wind the
pressure back to 0 before filling the
rocket, so it is very unlikely that both
#4 and #6 were at 130psi.

Our current assumption
is that flight #4 was at 120psi and
flight #6 was at 130psi or close to it.
For the next verification launches again
comparing water and foam we
will set the pressure regulator to one
setting and leave it there for all
flights to make sure we always have the
same pressure.

These are relatively close
to the measured altitude on flight #3
(365') and are also in close agreement
to flights from 2
weeks ago of 376' and 363'.

@130psi we get an
estimate of 396' (121m) for Clifford's
simulator and 400' (122m) for Dean's.

Flights 4 and 6
significantly deviate from these
predictions. They are roughly 20-25%
higher!

The rocket's
configuration is a spliced-pair on the
bottom with a 18mm hole in the tornado
tube to a second splice-pair in the
middle. This then joins via another tornado tube with a 15mm
hole to a 1.25L bottle at the
top.

Other observations

Just before launch #4
you can see that the foam level reaches
up to the top coupling. For the #6
launch you can see that the foam level
was half way up the top bottle. There
had been some residual foam left in
the rocket from the previous
flights.

The same rocket was used
in Doonside two weeks earlier and
launched at the same pressure with
1500mL of water only. It gave altitudes
of 376' and 363' which is consistent
with the first three flights without
foam.

When we filled the
rocket, a lot of the water drained into
the top bottle, when we set the rocket
up on the pad we had to squeeze the
bottle several times to get the water to
drain to the lower levels. This likely
produced more foam in the rocket.

Quite a few years
ago there was 1 flight we did
(day45) that also
showed a significant altitude boost
over a previous flight when we added
foam.

Sound analysis

When we look at the
sound produced by the rocket (as heard
on the ground), you can
get a sense of what's going on with the
thrust profile. Here is a comparison of
the 5 flights (1,2,3,4 and 6).

Flight 1,2 and 3 only
used water, while 4 and 6 had a small
amount of kids bubble bath added to the
water to make up the same amount by
volume.

In the first three you
can see a clear distinction in the water
and air phases. In flight 4 you can see
the extended air phase where the foam is
coming out, but you still see both
phases.

In flight 6, however, there does
not appear to be a clear distinction in
the two phases. The overall sound
amplitude is also lower than when
compared to water alone.

Here is a highlights video from
the day.

Next launch we will again try to fly some comparison flights
between water only and with foam. We had performed some
comparison tests several years ago, but
those flights used the more restricted Robinson couplings in the
rocket construction.

Polaron G2 Updates

We have continued to progress on the G2 as well. Here are
some more progress notes and photos on the
G2 build log.